At the highest levels of ComEd, executives are getting power line maintenance, repair and construction crews set for what could be a wild night.

"We are opening our emergency operations center at 5 p.m., being staffed with engineers and leadership ready to manage this storm. We're readying equipment and material in the event that there are outages as a result of the weather," said Fidel Marquez, ComEd.

The threat is real. Private forecasters have told the utility to prepare for 45 mph hour winds - enough to bend trees and break branches

"There's still plenty of leaves on the trees and those trees act as sails and help capture the wind. So, we expect there will be some tree damage as a result, and some damage to our equipment," Marquez said.

At the Morton Arboretum there's a lot of research that goes into determining the strength of trees - and the hidden hazards that can be exposed in a storm.

"Oftentimes when trees are damaged, there is a defect involved - whether it be decay or codominant stems, where two stems are coming up that are both the same size, and we really need to be looking out for those types of defects," said Jake Miesbauer, Morton Arboretum.